1. Field of the Invention
The subject invention generally relates to an air intake manifold for supplying air to a plurality of cylinders in an engine.
2. Description of the Related Art
Air intake manifolds supply a flow of an air or air/fuel mixture to the cylinders of an engine for combustion. The air intake manifold is typically mounted to a cylinder head of the engine, and defines a plurality of runners in fluid communication with the cylinders of the engine.
In a V-style engine, the air intake manifold is attached to a first cylinder head and a second cylinder head of the engine. As part of an engine coolant system, an engine coolant is circulated through a plurality of water-jackets in the engine and in each of the first and second cylinder heads. The engine coolant system further includes a coolant cross-over interconnecting the first and second cylinder heads in fluid communication. Frequently, the air intake manifold and the coolant cross-over are integrally formed from a metal, such as aluminum.
U.S. Pat. No. 3,931,811 (the '811 patent) discloses such a metal air intake manifold. The air intake manifold disclosed in the '811 patent is for use in a V-style engine and includes the coolant cross-over integrally formed with the metal air intake manifold for interconnecting fluid passageways in the first and second cylinder heads of the engine. Casting and milling operations are utilized to produce the metal air intake manifold. However, metal air intake manifolds are costly to produce because of both material costs of the metal as well as production costs associated with the casting and milling operations necessary to produce the metal air intake manifold. Additionally, it is desirable to minimize a weight of the air intake manifold to reduce an overall weight of a vehicle to thereby increase a fuel efficiency of the vehicle.
As a cost saving measure and to reduce the weight of the air intake manifold, manufacturers began producing the air intake manifold from a polymer, such as nylon 6, or nylon 6/6. While the polymer air intake manifold requires a lower cost to produce and weighs less than the metal air intake manifold, the engine coolant degrades the polymer material forming the air intake manifold. Accordingly, the polymer air intake manifolds do not include an integrally formed coolant cross-over.
U.S. Pat. No. 6,945,199 (the '199 patent) discloses an air intake manifold formed from a polymer material, which includes a coolant cross-over. The coolant cross-over is formed from a metal to prevent degradation by the engine coolant, and is mechanically attached to the polymer air intake manifold. While the '199 patent permits the use of polymer air intake manifolds, which reduced the overall cost and weight of the air intake manifold, there are still significant costs associated with the casting and milling operations necessary to produce the coolant cross-over from metal and attach the metal coolant cross-over to the polymer air intake manifold.
Accordingly, there remains a need for a coolant cross-over that is formed from a polymer, is resistant to degradation, reduces the overall weight of the air intake manifold, reduces the cost of producing the air intake manifold and reduces the number of manufacturing operations necessary to produce the air intake manifold.